Mineola Nature Preserve
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mineola Nature Preserve clear sky chart from 2005-11-06 to 2026-05-17.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	13% 6% 2 5% 4 4 4 3 5% 7% 47%	132302
	Night	12% 5% 2 5% 3 3 3 3 5% 7% 52%	130811
Transparency	Day	36% 3 9% 24% 20% 7%	135954
	Night	33% 3 9% 22% 23% 11%	135223
Seeing	Day	14% 7% 22% 27% 22% 8%	17121
	Night	14% 7% 25% 34% 18% 2	27045

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	14% 8% 3 5% 3 3 3 3 4 6% 49%	5289
	11th to 20th	Day	9% 4 2 3 2 3 3 3 5% 7% 59%	5310
	21st to end	Day	25% 9% 2 6% 3 2 2 2 2 4 41%	5812
February	1st to 10th	Day	22% 8% 2 7% 4 3 3 2 3 4 42%	1900
	11th to 20th	Day	21% 9% 2 6% 4 3 3 3 4 4 42%	2049
	21st to end	Day	21% 6% 2 5% 3 3 2 2 3 4 48%	1863
March	1st to 10th	Day	17% 9% 2 5% 3 3 3 3 5% 6% 43%	5046
	11th to 20th	Day	14% 5% 2 4 3 3 3 2 4 6% 53%	5090
	21st to end	Day	15% 7% 2 6% 4 4 4 3 5% 7% 44%	5583
April	1st to 10th	Day	16% 6% 2 6% 4 4 4 3 5% 7% 43%	2310
	11th to 20th	Day	16% 7% 2 6% 5% 4 3 3 5% 7% 41%	2485
	21st to end	Day	15% 6% 2 6% 5% 4 4 3 6% 6% 42%	2520
May	1st to 10th	Day	20% 7% 3 7% 4 4 4 4 4 6% 37%	5945
	11th to 20th	Day	15% 7% 3 7% 5% 4 4 4 5% 6% 41%	5941
	21st to end	Day	13% 6% 3 7% 5% 5% 5% 4 7% 8% 37%	6434
June	1st to 10th	Day	8% 4 2 6% 5% 4 6% 4 7% 8% 45%	2600
	11th to 20th	Day	6% 4 2 5% 5% 5% 5% 4 7% 10% 47%	2600
	21st to end	Day	5% 3 2 4 5% 4 5% 5% 7% 10% 50%	2600
July	1st to 10th	Day	9% 6% 2 7% 6% 5% 6% 5% 8% 10% 37%	5900
	11th to 20th	Day	3 3 1 4 3 3 4 4 6% 11% 58%	5900
	21st to end	Day	7% 6% 2 6% 5% 4 5% 4 6% 9% 46%	6422
August	1st to 10th	Day	3 1 1 2 2 3 3 3 5% 7% 69%	4234
	11th to 20th	Day	5% 2 1 3 3 3 4 4 6% 10% 57%	4119
	21st to end	Day	5% 4 2 5% 5% 6% 6% 5% 9% 10% 44%	4312
September	1st to 10th	Day	9% 5% 2 5% 4 4 4 3 5% 7% 50%	2225
	11th to 20th	Day	10% 5% 2 6% 4 6% 4 5% 6% 7% 46%	2200
	21st to end	Day	8% 4 1 3 4 4 4 3 6% 7% 57%	2200
October	1st to 10th	Day	6% 3 1 4 3 3 3 3 5% 7% 61%	2063
	11th to 20th	Day	13% 4 1 3 3 3 3 2 4 5% 59%	2000
	21st to end	Day	14% 5% 2 5% 3 2 3 2 3 4 58%	2200
November	1st to 10th	Day	13% 5% 2 5% 3 3 3 3 4 6% 53%	2058
	11th to 20th	Day	10% 5% 2 5% 3 3 3 2 4 6% 56%	2100
	21st to end	Day	18% 6% 2 4 3 3 3 2 4 5% 49%	1894
December	1st to 10th	Day	19% 6% 2 4 3 2 3 2 4 5% 49%	3030
	11th to 20th	Day	18% 7% 2 6% 4 4 4 3 5% 6% 42%	3481
	21st to end	Day	17% 9% 3 6% 3 3 3 2 4 5% 45%	4587
January	1st to 10th	Night	14% 6% 2 5% 3 3 3 2 4 4 53%	7634
	11th to 20th	Night	9% 4 1 3 2 2 2 2 3 6% 66%	7680
	21st to end	Night	26% 9% 2 6% 3 3 3 2 3 4 39%	8402
February	1st to 10th	Night	17% 7% 3 5% 3 3 3 3 4 5% 48%	2730
	11th to 20th	Night	19% 8% 3 5% 3 3 2 2 3 4 46%	2465
	21st to end	Night	18% 7% 2 4 3 3 3 2 3 5% 50%	1940
March	1st to 10th	Night	20% 9% 2 5% 3 4 3 3 4 5% 43%	5029
	11th to 20th	Night	12% 5% 2 5% 4 4 4 3 4 6% 52%	5090
	21st to end	Night	14% 6% 3 6% 3 4 4 2 5% 6% 48%	5588
April	1st to 10th	Night	12% 5% 2 4 3 4 4 3 6% 7% 50%	2310
	11th to 20th	Night	13% 5% 2 5% 3 4 3 4 5% 8% 47%	2082
	21st to end	Night	12% 5% 2 5% 3 4 3 3 5% 7% 50%	2100
May	1st to 10th	Night	17% 8% 3 8% 4 4 4 3 6% 7% 36%	4171
	11th to 20th	Night	12% 6% 3 6% 4 4 4 3 6% 7% 44%	4107
	21st to end	Night	11% 6% 3 5% 3 3 4 4 6% 9% 47%	4443
June	1st to 10th	Night	5% 3 2 4 4 3 4 3 7% 10% 55%	1800
	11th to 20th	Night	4 4 1 4 3 3 4 3 5% 7% 64%	1800
	21st to end	Night	4 3 1 4 4 4 4 4 6% 9% 59%	1800
July	1st to 10th	Night	6% 4 2 6% 4 5% 6% 5% 7% 12% 43%	4078
	11th to 20th	Night	3 2 1 3 2 3 3 3 5% 11% 64%	4077
	21st to end	Night	4 3 2 4 5% 5% 4 4 6% 9% 53%	4449
August	1st to 10th	Night	1 1 2 2 2 3 2 5% 8% 74%	2926
	11th to 20th	Night	4 2 1 3 2 2 4 3 6% 12% 62%	2937
	21st to end	Night	4 2 1 3 3 4 5% 5% 7% 9% 57%	3586
September	1st to 10th	Night	8% 4 2 4 4 3 4 4 7% 7% 54%	2170
	11th to 20th	Night	10% 3 2 5% 3 3 3 3 5% 7% 55%	2200
	21st to end	Night	6% 3 1 4 3 3 3 3 6% 7% 62%	2200
October	1st to 10th	Night	6% 2 1 3 2 2 3 3 4 6% 67%	2315
	11th to 20th	Night	11% 4 1 3 2 2 3 2 3 6% 64%	2400
	21st to end	Night	15% 4 2 3 2 2 2 2 3 4 60%	2640
November	1st to 10th	Night	11% 5% 2 4 2 2 2 3 3 5% 60%	2460
	11th to 20th	Night	8% 5% 2 4 3 3 3 3 4 6% 57%	2520
	21st to end	Night	15% 6% 2 5% 3 3 3 3 3 5% 51%	2723
December	1st to 10th	Night	18% 6% 3 5% 3 2 3 2 3 4 51%	4380
	11th to 20th	Night	17% 7% 3 6% 4 3 3 2 3 4 47%	4946
	21st to end	Night	14% 9% 3 6% 3 2 2 2 3 4 51%	6633

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	38% 2 7% 27% 24% 3	5290
	11th to 20th	Day	27% 2 6% 27% 32% 7%	5310
	21st to end	Day	51% 1 3 14% 21% 10%	5812
February	1st to 10th	Day	49% 2 3 17% 21% 9%	1900
	11th to 20th	Day	48% 2 5% 20% 18% 7%	2059
	21st to end	Day	43% 2 5% 15% 24% 12%	1863
March	1st to 10th	Day	44% 2 4 16% 21% 13%	5046
	11th to 20th	Day	36% 1 5% 18% 19% 21%	5090
	21st to end	Day	42% 2 9% 22% 20% 5%	5585
April	1st to 10th	Day	42% 2 9% 21% 18% 8%	2310
	11th to 20th	Day	43% 2 9% 18% 21% 7%	2485
	21st to end	Day	42% 3 8% 22% 22% 4	2520
May	1st to 10th	Day	50% 3 9% 25% 11% 2	5983
	11th to 20th	Day	46% 3 8% 20% 21% 2	5945
	21st to end	Day	44% 4 11% 22% 16% 3	6447
June	1st to 10th	Day	34% 5% 15% 30% 14% 2	2600
	11th to 20th	Day	31% 5% 15% 28% 17% 4	2600
	21st to end	Day	27% 5% 13% 32% 19% 2	2600
July	1st to 10th	Day	39% 8% 21% 25% 7%	5836
	11th to 20th	Day	20% 5% 17% 39% 18% 1	5831
	21st to end	Day	34% 6% 13% 34% 12% 1	6240
August	1st to 10th	Day	14% 4 12% 34% 31% 5%	4220
	11th to 20th	Day	22% 4 17% 43% 14% 1	4158
	21st to end	Day	31% 8% 17% 29% 13% 1	4311
September	1st to 10th	Day	34% 3 9% 23% 21% 9%	2225
	11th to 20th	Day	37% 5% 11% 21% 19% 7%	2200
	21st to end	Day	27% 3 8% 23% 27% 12%	2200
October	1st to 10th	Day	14% 1 6% 13% 28% 36%	3362
	11th to 20th	Day	20% 1 3 22% 31% 23%	3240
	21st to end	Day	26% 2 4 26% 34% 9%	3538
November	1st to 10th	Day	34% 2 7% 22% 27% 9%	2058
	11th to 20th	Day	31% 2 8% 20% 28% 12%	2100
	21st to end	Day	40% 2 5% 20% 25% 8%	1894
December	1st to 10th	Day	39% 2 5% 24% 25% 5%	3030
	11th to 20th	Day	45% 2 5% 15% 24% 10%	3479
	21st to end	Day	44% 1 4 20% 24% 6%	4587
January	1st to 10th	Night	36% 2 6% 22% 29% 5%	7635
	11th to 20th	Night	23% 1 5% 20% 35% 16%	7680
	21st to end	Night	52% 1 3 14% 19% 11%	8402
February	1st to 10th	Night	39% 2 6% 19% 22% 12%	2730
	11th to 20th	Night	44% 2 5% 18% 22% 9%	2465
	21st to end	Night	40% 2 6% 16% 22% 14%	1940
March	1st to 10th	Night	46% 1 4 13% 20% 16%	5029
	11th to 20th	Night	35% 1 7% 15% 19% 22%	5090
	21st to end	Night	40% 2 8% 21% 24% 7%	5588
April	1st to 10th	Night	34% 3 11% 21% 18% 12%	2310
	11th to 20th	Night	37% 3 10% 19% 21% 11%	2082
	21st to end	Night	35% 3 9% 21% 27% 5%	2100
May	1st to 10th	Night	48% 3 10% 24% 13% 3	4198
	11th to 20th	Night	40% 4 14% 17% 23% 2	4108
	21st to end	Night	35% 4 15% 27% 12% 8%	4452
June	1st to 10th	Night	25% 4 17% 31% 20% 3	1800
	11th to 20th	Night	21% 4 14% 34% 21% 6%	1800
	21st to end	Night	23% 4 15% 29% 26% 4	1800
July	1st to 10th	Night	33% 7% 22% 30% 8%	4035
	11th to 20th	Night	17% 4 20% 39% 17% 3	4026
	21st to end	Night	26% 6% 17% 34% 14% 3	4320
August	1st to 10th	Night	10% 3 12% 33% 35% 7%	2916
	11th to 20th	Night	18% 3 14% 44% 17% 4	2964
	21st to end	Night	22% 6% 19% 30% 21% 3	3586
September	1st to 10th	Night	28% 4 12% 24% 21% 11%	2170
	11th to 20th	Night	30% 3 10% 26% 21% 9%	2200
	21st to end	Night	23% 3 7% 23% 30% 14%	2200
October	1st to 10th	Night	13% 1 5% 15% 23% 43%	3783
	11th to 20th	Night	17% 1 4 17% 34% 27%	3899
	21st to end	Night	25% 2 3 21% 31% 17%	4252
November	1st to 10th	Night	30% 1 7% 20% 27% 14%	2460
	11th to 20th	Night	29% 2 6% 20% 27% 15%	2520
	21st to end	Night	38% 2 6% 19% 26% 10%	2723
December	1st to 10th	Night	39% 2 5% 19% 27% 8%	4380
	11th to 20th	Night	42% 2 6% 15% 24% 12%	4947
	21st to end	Night	40% 1 5% 19% 27% 8%	6633

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	24% 12% 38% 20% 5% 1	330
	11th to 20th	Day	19% 17% 40% 15% 8%	330
	21st to end	Day	25% 16% 39% 16% 3	363
February	1st to 10th	Day	28% 12% 39% 15% 5%	330
	11th to 20th	Day	30% 20% 36% 12% 2	330
	21st to end	Day	29% 19% 37% 12% 3	273
March	1st to 10th	Day	25% 15% 37% 19% 4	330
	11th to 20th	Day	23% 19% 38% 15% 4 1	330
	21st to end	Day	18% 17% 39% 20% 6%	363
April	1st to 10th	Day	24% 13% 36% 21% 5% 1	330
	11th to 20th	Day	24% 14% 32% 20% 9% 1	523
	21st to end	Day	20% 10% 34% 25% 8% 2	540
May	1st to 10th	Day	17% 9% 35% 29% 9% 1	732
	11th to 20th	Day	15% 8% 26% 32% 17% 3	756
	21st to end	Day	13% 5% 25% 34% 19% 4	789
June	1st to 10th	Day	8% 2 15% 34% 31% 10%	730
	11th to 20th	Day	6% 1 15% 40% 30% 8%	730
	21st to end	Day	4 2 10% 34% 35% 15%	730
July	1st to 10th	Day	7% 2 7% 33% 36% 14%	721
	11th to 20th	Day	3 1 4 36% 38% 18%	718
	21st to end	Day	5% 2 5% 30% 41% 18%	794
August	1st to 10th	Day	4 1 5% 31% 41% 18%	726
	11th to 20th	Day	7% 1 4 29% 45% 13%	689
	21st to end	Day	9% 2 4 22% 40% 23%	583
September	1st to 10th	Day	6% 1 9% 24% 38% 21%	355
	11th to 20th	Day	4 1 8% 28% 40% 19%	330
	21st to end	Day	11% 3 10% 28% 32% 16%	330
October	1st to 10th	Day	5% 16% 35% 36% 7%	330
	11th to 20th	Day	10% 5% 31% 29% 18% 7%	330
	21st to end	Day	23% 10% 25% 26% 12% 5%	363
November	1st to 10th	Day	19% 6% 27% 31% 13% 4	330
	11th to 20th	Day	15% 8% 30% 36% 9% 2	330
	21st to end	Day	23% 13% 31% 23% 10% 1	330
December	1st to 10th	Day	24% 10% 34% 22% 8% 2	330
	11th to 20th	Day	24% 13% 34% 23% 7%	330
	21st to end	Day	24% 14% 34% 24% 3 1	363
January	1st to 10th	Night	19% 11% 33% 30% 7%	1050
	11th to 20th	Night	20% 14% 32% 28% 6% 1	1050
	21st to end	Night	21% 11% 34% 30% 5%	1155
February	1st to 10th	Night	21% 11% 37% 26% 5%	1050
	11th to 20th	Night	25% 13% 32% 26% 3	831
	21st to end	Night	24% 16% 36% 21% 4	556
March	1st to 10th	Night	21% 10% 36% 26% 6%	630
	11th to 20th	Night	18% 11% 34% 30% 7%	630
	21st to end	Night	15% 9% 39% 30% 7%	693
April	1st to 10th	Night	16% 10% 39% 29% 7%	630
	11th to 20th	Night	15% 11% 38% 26% 9% 1	623
	21st to end	Night	15% 7% 39% 29% 10% 1	630
May	1st to 10th	Night	13% 7% 37% 34% 9% 1	630
	11th to 20th	Night	12% 6% 28% 36% 16% 2	609
	21st to end	Night	9% 5% 26% 40% 19% 2	650
June	1st to 10th	Night	6% 2 13% 42% 34% 3	600
	11th to 20th	Night	6% 16% 50% 26% 2	600
	21st to end	Night	3 2 11% 39% 38% 7%	600
July	1st to 10th	Night	5% 2 4 42% 41% 5%	585
	11th to 20th	Night	3 1 7% 38% 45% 6%	582
	21st to end	Night	2 1 5% 40% 44% 8%	657
August	1st to 10th	Night	2 1 4 40% 47% 6%	597
	11th to 20th	Night	7% 1 2 38% 45% 8%	594
	21st to end	Night	5% 1 5% 35% 47% 8%	660
September	1st to 10th	Night	9% 1 7% 35% 43% 6%	600
	11th to 20th	Night	11% 1 8% 33% 42% 5%	600
	21st to end	Night	7% 1 12% 38% 37% 5%	600
October	1st to 10th	Night	7% 1 13% 45% 30% 4	715
	11th to 20th	Night	12% 4 23% 39% 19% 3	800
	21st to end	Night	17% 6% 26% 33% 17% 1	880
November	1st to 10th	Night	14% 4 25% 38% 17% 1	820
	11th to 20th	Night	11% 6% 33% 38% 11% 1	840
	21st to end	Night	18% 12% 30% 28% 11% 1	1043
December	1st to 10th	Night	19% 9% 31% 35% 7%	1050
	11th to 20th	Night	22% 9% 29% 35% 6%	1050
	21st to end	Night	20% 10% 33% 31% 6%	1155

Page generated at 2026-05-14 00:58:54. Version ac07

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